In high rise building construction an important consideration is to provide containment of a fire to its floor of origin. One area of particular concern is the perimeter of each floor where there is typically a gap between the floor slab and the exterior curtain wall structure. At this location, any opening provides a ready path for fire to spread to the level above. Therefore, it has been known to plug any openings between the curtain wall and the floor perimeter with heat resistant insulating materials. These insulating materials have included sheets of curtain wall insulation that cover the interior of the spandrel area of the curtain wall, as well as "safing" which is inserted into any openings between levels and, in particular, into the gap between the curtain wall insulation and the perimeter of the floor slab.
A shortcoming of the typical fire containment insulation arrangements of the prior art is that they rely upon the curtain wall structure for support. The relatively lightweight materials (e.g., aluminum) from which curtain wall framing members are typically constructed often provide considerably less heat resistance than the fire containment insulation itself. As a result, it is sometimes found that failure of the fire containment arrangement occurs when the insulation falls out of position due to softening of the curtain wall members to which it was attached. The present invention overcomes this drawback thereby providing fire containment of greater duration.